Using L 5178Y cells and normal mouse bone marrow cells as a test system, the objectives of this study will be to investigate the mechanism(s) of selective toxicity of D-glucosamine for tumor cells and to assess the ability of this drug to selectively potentiate the antineoplastic acitivity of drugs which affect cellular DNA and glycoprotein synthesis. Studies will be performed with cultured L 5178Y cells to screen for effective drug combinations. Further studies will be made at the biochemical level to determine whether potentiation is the result of disturbances in cellular ribo- and deoxyribonucleotide metabolism or of cellular membrane damage produced by D-glucosamine. Cytotoxicity studies on cultures L 5178Y and normal bone marrow cells will be used to determine a therapeutic index for effective drug combinations. Lastly, drug combinations with high therapeutic indices will be tested for their antitumor activity in animals.